In this week's Varsity Numbers, Bill Connelly revisits some measures and concepts: Adjusted Scores, Covariance, and momentum (or whatever you choose to call it).
08 Jan 2012
by Aaron Schatz
There really are no weak sisters in this year's NFC playoffs, as all four of the NFC teams playing on wild card weekend ranked 12th or higher in total DVOA. The two NFC South teams, New Orleans and Atlanta, have been particularly hot in the second half of the season. Detroit is trying to prove that they aren't just happy to be here, and the Giants are trying to prove that their impressive wins in the last two weeks show they've overcome yet another second-half meltdown.
For those who may be unfamiliar with the Football Outsiders stats, they are explained at the bottom of the page. Scroll down or click this link. Please remember that game charting data is still incomplete, but represents most of Weeks 1-14.
All readers can click here for in-game discussion on our message boards. If you have FO Premium, you can click here to see all the matchup of DVOA splits for this game.
Our first NFC wild card game is a repeat from Week 13, when the Saints beat Detroit 31-17. The Saints got off to a 24-7 start, then withstood a small Detroit comeback in the third quarter. Remarkably, the Lions actually outgained the Saints in net yardage, 466 to 438. However, the Lions had fewer yards per play (6.8 vs. 7.2 for New Orleans), the game's only turnover, and a lot of penalties: 11 flags for 107 yards.
It's no secret that the passing game is now a bigger part of the NFL than ever before, and Detroit epitomizes this. Detroit ran the ball on a league-low 33 percent of plays, despite the fact that they won 10 games and thus had some time running out the clock. And no team uses shotgun more than Detroit, which went shotgun on 68 percent of plays this year. The Saints had a poor defense this year, and it was even worse when opposing quarterbacks were in shotgun. The Saints had 4.0% DVOA (19th) against quarterbacks under center, but 31.0% DVOA (29th) against quarterbacks in shotgun.
The Saints ranked 17th in DVOA against No. 1 receivers, which is a little bit better than their overall pass defense but not really something that gives you confidence in their ability to cover Calvin Johnson. Johnson had just 69 yards with no touchdowns in the first Saints-Lions game, and it's hard not to argue that this was the best-case scenario for the Saints. He should do better in their second meeting.
The Saints have an interesting series of strengths and weaknesses when it comes to pass coverage. The biggest strength is Jabari Greer at left cornerback (the offense's right side). Greer has a 69 percent Success Rate in our game charting as compiled so far. However, his strength is very clearly against short- and medium-length passes in man coverage. The Saints are fourth in the league in defensive DVOA against passes to the short right (up to 15 yards through the air) but 22nd in defensive DVOA against passes to the deep right (over 15 yards through the air). Greer has six passes defensed (at least, that we've charted) against deep passes of 25 or more yards. But when he's playing closer to the line with safety help behind him, those safeties don't really do the best job of covering the deep areas. On the other side, game charting so far has second-year cornerback Patrick Robinson as roughly league-average (55 percent Success Rate, 6.9 yards per play).
The Saints also tend to leave some open holes right in the middle of the field, and they have the worst defensive DVOA in the league on "short middle" passes. By comparison, the Detroit offense ranks eighth in DVOA on such passes. This is where tight end Brandon Pettigrew does his best work. Pettigrew has 11.5% DVOA, 72 percent catch rate and 7.1 yards per pass target on passes in the middle of the field, but -14.7% DVOA, 62 percent catch rate, and 5.5 yards per pass target on passes to the sides.
New Orleans big blitzes on 28 percent of pass plays, by far the most in the league. However, based on our numbers, Matthew Stafford has been very good against big blitzes this year. Our charting so far has him at 6.5 yards per play with 3-4 pass rushers, 5.9 yards per play with five pass rushers, but 8.2 yards per play with six or more pass rushers. Watch for Stafford dumping the ball off to Kevin Smith and Maurice Morris for nice gains on those big blitzes -- those constant blitzes are a big reason why the Saints rank 28th in DVOA against running backs as receivers.
The Lions' running game improved in the second half of the year, going from -5.8% DVOA (26th) to 5.8% DVOA (ninth), but it still doesn't matter much because they still don't run much. The Saints are below-average against the run and particularly struggle in short-yardage situations (73 percent conversion on power runs, 30th in the NFL) but the Lions aren't much better in those situations (52 percent conversion on power runs, 28th in the NFL).
One other interesting note: All year, the Detroit offense has started games slow, with -14.8% offensive DVOA in the first quarter (27th in the NFL). After the first quarter, Detroit's offensive DVOA is 19.2%, which is fifth in the league for quarters 2-4.
One element in Detroit's favor is that in the first game, New Orleans was not facing a Detroit defense that was at full strength. Ndamukong Suh was under suspension, and the Lions' two best defensive backs, Chris Houston, and Louis Delmas, missed the game with injuries. All three players will play this week. But how much can they help slow down a red-hot Saints offense?
Offense is where you really see how the Saints have improved over the last few weeks of the season. In Weeks 1-9, the Saints had 25.1% offensive DVOA. Plenty good, of course, but not superlative. Since Week 10, the Saints have 54.7% offensive DVOA. Both the run and the pass have improved. Meanwhile, the Detroit defense has declined a little bit in the second half of the year, going from sixth in DVOA in the first nine weeks (-6.3%) to 13th in the last eight weeks (-1.8%). The injuries and Suh suspension probably have a little bit to do with this.
Third downs should be interesting, as the Saints are the No. 1 DVOA offense on third downs and the Lions are the No. 1 DVOA defense. The Lions are best (at least, when compared to an average defense) in third-and-short situations. The Saints, on the other hand, are only average in third-and-short situations but just ridiculous when there are four or more yards to go. On third or fourth down with four or more yards to go, the Saints converted half the time. Green Bay was the only other offense above 40 percent. In addition, Brees threw only two interceptions all year on third down. (He also had one on fourth-and-short.)
FO numbers suggest the way to stop Brees is to blitz him. Our charting so far has him with 8.2 yards per play against 3-4 pass rushers, 6.7 yards per play against five pass rushers, and just 4.7 yards per play against a big blitz of six or more. Last year, Brees also was better with fewer pass rushers, although the numbers were closer: 6.7 yards per play against 3-4 pass rushers, 6.2 against five, and 5.7 against six or more. In general, Brees doesn't struggle by throwing a lot of incomplete passes against the big blitz. But it is easier to sack him or limit him to shorter underneath dumpoffs. If the Lions do want to big blitz Brees, it will mean deviating from their usual strategy, as they sent more than four pass rushers on just 18 percent of pass plays (30th in the NFL). Unless they blitz, I don't expect to see Brees taking many sacks. While the Lions' best unit is the defensive line, they are actually only league-average in Adjusted Sack Rate, and of course Brees is excellent at getting rid of the ball (and the Saints are third in ASR on offense).
In our defense vs. receivers numbers, the Lions rank in the top 10 against each kind of receiver except for "other wide receivers," where they are 16th. In the first game, they had the biggest trouble with Robert Meachem (3-of-6 for 119 yards, including a 67-yard touchdown) and Jimmy Graham (8-of-10 for 89 yards).
We're generally all so busy talking about how great the Saints passing game is that we overlook just how efficient their running game is -- second in DVOA behind Carolina and first in Adjusted Line Yards by a wide margin. The Lions' run defense is only mediocre, ranked 20th in DVOA and 15th in Adjusted Line Yards. In particular, the Lions had a problem giving up long highlight runs (19th in Second-Level Yards, 28th in Open-Field Yards) while the Saints get some long runs and lots and lots of good, 5-10 yard runs (first in SLY, 13th in OFY). Watch out for the Saints running around the right end. The Detroit defense was No. 1 against runs left end but 30th against runs right end.
The Lions get flagged a lot on offense, but it is their flags on defense that really stand out. The Lions were fourth in the league with 145 penalties this year (including declined and offsetting). A couple of unnecessary roughness penalties got all the press, but a bigger problem for Detroit is that they were second in the league with 24 of the various "offside" penalties: defensive offside, encroachment, and neutral zone infraction.
Probably not an area of great impact in this game, although the Saints are rated higher than the Lions. You've got to give the Saints' punter and punt coverage team some credit for ranking sixth in net punt value. They didn't exactly get a lot of in-game practice. Darren Sproles had a good year as a kickoff and punt return man, but not a great one. The Lions' special teamers are mostly a bunch of JAGs (a.k.a. "just a guy"). The exception is John Wendling, one of the best gunners in the league. He was fourth in the league with 17 special teams plays this year, after ranking second with 22 in 2010. It's nice that Jason Hanson was able to stick around Detroit long enough to see the team finally make the playoffs, but he's not really a good kicker anymore. With Hanson kicking for Detroit and Kasay for New Orleans, the field-goal kickers in this game are a combined 83 years old. George Blanda is waiting in the wings in case anyone gets injured.
Hey, Detroit, it's been fun, but New Orleans is the hottest team in the league right now and they've got the home crowd behind them. It probably won't be a blowout, but they should be able to outscore the Lions.
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A few people have asked about my proclamation that the Falcons were the most consistent team of the year, and in fact the most consistent team of the last 20 years. Didn't Atlanta tend to play well against bad teams, then lose to good teams? Well, yes, actually -- but as a reader pointed out here, that translates into consistency in DVOA terms. The Falcons played at roughly the same quality all season -- it was the quality of the opponent that changed. So are the Giants the kind of good team that the Falcons generally lost to, or the kind of bad team that the Falcons generally beat? The answer is probably somewhere in the middle.
Although this game looks like a better defensive battle than Detroit-New Orleans, there still is a good chance that we'll see plenty of scoring and long, extended drives. Both of these teams struggle to get off the field on third down. The Falcons rank 11th in offense DVOA on third down, but 27th on defense; the Giants rank seventh in offensive DVOA on third down, but 23rd on defense.
The biggest question here is whether winning their final two games -- and allowing only 14 points in each one -- shows that the Giants have finally arrested their usual second-half defensive slump. The Giants' defensive DVOA over the first eight games of the season was -1.5%, which ranked ninth in the league. During Weeks 10-15, the Giants had a defensive DVOA of 22.9%, which was the second worst figure in the league over those six weeks. But in their last two games, the Giants' defensive DVOA is back down to -3.5%. Both pass and run defense declined during the downturn, and both pass and run defense rebounded during the final two games.
Conventional wisdom says that this year we saw a big shift in the Atlanta offense, which now passes the ball more with the running game declining. Actually, this year really was no different from last year. In 2010, the Falcons passed on 58 percent of plays. This year, it was 59 percent of plays. In 2010, the Falcons ranked eighth in pass offense DVOA but 26th in run offense. This year, they ranked eighth in pass offense and 25th in run offense. Despite the struggles of their running game, the Falcons still prefer to run the ball on first down. They ran on 55.5 percent of first downs this year, which ranked ninth in the NFL.
Looking at the numbers, you definitely see the difference between how the Falcons used their two main wide receivers. Julio Jones generally plays on the left, while Roddy White is on the right. Roddy White runs shorter routes more frequently than Jones does, although White runs plenty of deep routes as well. Put it together and you get this nugget: White was the target on 85 passes marked "short right," which was almost as many passes as Jones' entire season total of 96 targets. White was pretty good on those short right passes too, catching 65 percent of them (as opposed to just 46 percent of passes marked "short left" or "short middle").
The Giants tend to move their cornerbacks around a lot more than most other teams, with both Corey Webster and Aaron Ross playing sometimes on the left and sometimes on the right. Webster was clearly the better corner according to game charting, with 6.3 yards per play and a 52 percent Success Rate. Ross comes out with 10.2 yards per pass -- one of the worst figures in the league -- and a 45 percent Success Rate. If one Atlanta receiver was a lot better than the other one, it would be easy to assign Webster to him, but that's not really the case. I'm guessing that Matt Ryan's first look will generally be towards whoever Ross is covering.
Meanwhile, Antrel Rolle, the safety who often becomes slot cornerback in the nickel, allowed 8.4 yards per play with a 48 percent Success Rate. The "defense vs. receivers" numbers suggest that the Giants have trouble covering those slot receivers when opponents spread the field. The Giants ranked 30th in DVOA against "other receivers," and ranked 31st allowing 64.3 yards per game to these receivers. For Atlanta, that would be Harry Douglas.
The best defense for the Giants may be to bring pressure. Despite some upheaval on the offensive line -- Sam Baker was benched at midseason and replaced with Will Svitek -- the Falcons did a good job of preventing sacks, finishing seventh with a 5.1 percent Adjusted Sack Rate. Benching Baker only improved things, as the Falcons had a 3.6 percent ASR in the final 10 games of the season. For all the accolades heaped on their defensive line, the Giants actually were just tenth in ASR at 7.4 percent. However, our charting suggests the Giants are excellent when big blitzing, allowing just 2.7 yards per play when rushing six or more. And Matt Ryan struggles against the big blitz, with 4.4 yards per play against six or more pass rushers but 7.2 yards per play otherwise.
Of all the units on all the teams in the postseason, the Falcons defense may have the biggest gap between reputation and performance. Very few people think of the Falcons as one of the better defenses in the league, but they ranked sixth in DVOA and finished the season second in weighted DVOA, behind only the Chicago Bears. They aren't a great defense -- this season, there really were no great defenses -- but they're a very good and underrated defense. However, Eli Manning should still be able to pass on them, as the Falcons are better against the run (third) than the pass (10th).
Like the Giants, the Falcons have a big dichotomy between their top two cornerbacks. But unlike the Giants, the Falcons generally keep those cornerbacks on the same side of the field. That means you can generally figure out who you want to throw to by avoiding Brent Grimes and the right side of the field. The Falcons allowed 60.8% DVOA on deep passes to the left side of the field, which ranked 29th in the league. But they were the best team in the league against deep middle passes, and ranked sixth against deep right passes. You can also see this split in the game charting stats for the Atlanta cornerbacks: Grimes has allowed 6.0 yards per pass with a 66 percent Success Rate, while Robinson has allowed 9.1 yards per pass with a 53 percent Success Rate. Grimes should play Sunday, although he's being held out of midweek practices as a precaution as he is coming back from a knee injury.
The ability to avoid Grimes (and the couple of games he missed with that injury) helps to explain the weird splits of Atlanta DVOA against different types of receivers. The Falcons ranked 28th against the opponents No. 1 receiver, 12th against the No. 2 receiver, and second in the league against "other receivers." They also ranked first in the league against tight ends and seventh against running backs. Did opponents understand this? I'm not sure what they saw on the tape because opponents' tendencies worked the exact opposite of Atlanta's strengths. Opponents only threw to their No. 1 receiver on 20 percent of passes against Atlanta, the lowest figure in the league, even though that was the biggest weakness of the Falcons secondary. They threw to their tight ends on 26 percent of passes, the highest in the league, even though that was the biggest strength of the Falcons secondary.
Of course, the Giants might consider either Hakeem Nicks or Victor Cruz their No. 1 receiver, and either one can go deep, so they can pretty much pick who they want to put up against Grimes and who they want to put up against Robinson on whatever plays. (Plus, of course, Mario Manningham often will come in to play outside receiver with Cruz kicking inside.) The fact that the Falcons can shut down Jake Ballard doesn't matter much since the Giants don't throw to the tight end very much, although Ballard had a great season in limited use (sixth in tight end DYAR and DVOA).
I don't foresee Eli Manning seeing a lot of pass pressure in this game. The Giants ranked sixth in offensive ASR (basically tied with the Falcons) while the Falcons defense was just 24th in defensive ASR. Even if they get frustrated by the lack of pass rush, the Falcons should avoid big-blitzing Eli Manning. In charting compiled so far, Manning is averaging 11.7 yards per play with six or more pass rushers, the highest figure in the league. (That figure will likely go down a little bit once we have the whole season charted. It's a bit over-influenced by that 74-yard touchdown pass where Cruz broke like 30 Philadelphia tackles. But even without that play, Manning's average of 9.6 yards per play is much higher than the 7.4 yards per play he averages otherwise.)
It's well known that the Giants' vaunted running game hit the skids this year. They dropped to 20th in DVOA, and ended up dead last in total rushing yards because they really shied away from using that struggling running game. In 2010, the Giants ran 53 percent of the time on first down, 11th in the NFL. This year, they ran 43 percent of the time on first down, 31st in the NFL. Given how well the Falcons played against the run this year, it's hard to imagine the Giants running any more in this game than they did during the regular season.
When the Giants do need to run the ball, the numbers suggest they would be better off going with those Brandon Jacobs power runs up the middle rather than Ahmad Bradshaw around the edge. The Falcons ranked third in Adjusted Line Yards overall, but they actually struggled against runs up the gut, ranking just 25th in ALY on these runs. They also were just average preventing conversions on short-yardage runs. Of course, the Giants were one of the worst teams in the league in that situation (ranked 27th).
Both teams ended up around league average in special teams this year. Atlanta is pretty much mediocre across the board, although Matt Bryant was a bit above average on field goals. The Giants have more pronounced strengths and weaknesses. Their returns weren't very good, but they're pretty good on both kickoffs and punts.
This is the closest game of the weekend. It is the game where Football Outsiders numbers most disagree with conventional wisdom, and the game we see as the most likely upset. I would even lean a bit towards Atlanta if their strengths did a better job of lining up with the strengths of the Giants. However, the ability to stop the run isn't that big a deal against the current Giants. With a tepid pass rush, it's easy to see Eli Manning standing back in the pocket and finding the weak spots in the Atlanta secondary. On the other hand, the Falcons pass protection has been strong, so Matt Ryan should be able to move the ball pretty well too. That makes this game a toss-up.
DVOA (Defense-adjusted Value Over Average) breaks down each play of the season and compares it to the NFL average based on situation and opponent. You'll find it explained further here. Since DVOA measures ability to score, a negative DVOA indicates a better defense and worse offense, and a positive DVOA indicates a better offense and worse defense.
SPECIAL TEAMS numbers are different; they represent value in points of extra field position gained compared to NFL average. Field goal rating represents points scored compared to average kicker at same distances. All special teams numbers are adjusted by weather and altitude; the total is then translated into DVOA so it can be compared to offense and defense. Those numbers are explained here.
Each team is listed with DVOA for offense and defense, total along with rush and pass, and rank among the 32 teams in parentheses. (If the DVOA values are difficult to understand, it is easy to just look at the ranks.) We also list red zone DVOA and WEIGHTED DVOA (WEI DVOA), which is based on a formula which drops the value of games early in the season to get a better idea of how teams are playing now (explained here).
Each team also gets a chart showing their performance this year, game-by-game, according to total DVOA. In addition to a line showing each game, another line shows the team's trend for the season, using a rolling average of the last five games. Note that even though the chart appears in the section for when each team has the ball, it represents total performance, not just offense.
29 comments, Last at 08 Jan 2012, 4:38pm by Aaron Brooks Good Twin